An optical signal processing device such as a reconfigurable optical add/drop multiplexer (ROADM) has been known in a field of a wavelength division multiplexing (WDM) optical communication. The processing device requires a wiring structure for dividing input WDM signals for each wavelength and collecting respective divided signal components for each wavelength.
U.S. Pat. No. 8,768,116 disclosed an optical cross-connect mechanism including a first connector stack stacked in one direction and a second connector stack stacked in another direction orthogonal to the relevant one direction, as the above wiring structure. This mechanism provides a lens to a tip end of each of optical fibers held by the first connector stack and the second connector stack.